#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#define BUFFER_SIZE 8
struct Products
{
	int buffer[BUFFER_SIZE];
	/*保证存取操作的原子性 互斥性*/
	pthread_mutex_t locker;
	/*是否可读*/           
	pthread_cond_t notEmpty;
	/*是否可写*/  
	pthread_cond_t notFull;
	int posReadFrom;
	int posWriteTo;
};

int BufferIsFull(struct Products* products)
{
	if ((products->posWriteTo + 1) % BUFFER_SIZE == products->posReadFrom)
	{
		return (1);
	}
	return (0);
}

int BufferIsEmpty(struct Products* products)
{
	if (products->posWriteTo == products->posReadFrom)
	{
		return (1);
	}
	return (0);
}

/*制造产品*/
void Produce(struct Products* products, int item)
{
	/*原子操作*/
	pthread_mutex_lock(&products->locker);
	/*无空间可写入*/
	while (BufferIsFull(products))
	{
		pthread_cond_wait(&products->notFull, &products->locker);
	} 
	/*写入数据*/
	products->buffer[products->posWriteTo] = item;
	products->posWriteTo++;
	if (products->posWriteTo >= BUFFER_SIZE)
		products->posWriteTo = 0;
	/*发信*/
	pthread_cond_signal(&products->notEmpty);
	/*解锁*/
	pthread_mutex_unlock(&products->locker);
}

int Consume(struct Products* products)
{
	int item;
	pthread_mutex_lock(&products->locker);
	/*为空时持续等待,无数据可读*/
	while (BufferIsEmpty(products))
	{
		pthread_cond_wait(&products->notEmpty, &products->locker);
	}
	/*提取数据*/
	item = products->buffer[products->posReadFrom];
	products->posReadFrom++;
	/*如果到末尾,从头读取*/
	if (products->posReadFrom >= BUFFER_SIZE)
		products->posReadFrom = 0;
	pthread_cond_signal(&products->notFull); 
	pthread_mutex_unlock(&products->locker);
	return item;
}

#define END_FLAG (-1)
struct Products products;
void* ProducerThread(void* data)
{
	int i;
	for (i = 0; i < 16; ++i)
	{
		printf("producer: %d\n", i);
		Produce(&products, i);
	}
	Produce(&products, END_FLAG);
	return NULL;
}

void* ConsumerThread(void* data)
{
	int item;
	while (1)
	{
		item = Consume(&products);
		if (END_FLAG == item)
			break;
		printf("consumer: %d\n", item);
	}
	return (NULL);
}

int main(int argc, char* argv[])
{
	pthread_t producer;
	pthread_t consumer;
	int result;
	pthread_create(&producer, NULL, &ProducerThread, NULL);
	pthread_create(&consumer, NULL, &ConsumerThread, NULL);
	pthread_join(producer, (void *)&result);
	pthread_join(consumer, (void *)&result);
	exit(EXIT_SUCCESS);
}
